From fe6ac99a29ec207c9c5f4421f3fed62fd5bc9d45 Mon Sep 17 00:00:00 2001
From: Matthew Nelson <developer@matthewnelson.io>
Date: Tue, 5 Mar 2024 09:13:12 -0500
Subject: [PATCH] Fix `Closeable.use` `NullPointerException` (#1453)

* Fix Cloneable.use NullPointerException

* Add assertNull
---
 okio/src/commonMain/kotlin/okio/Okio.kt     |  9 +++++----
 okio/src/nonWasmTest/kotlin/okio/UseTest.kt | 10 ++++++++++
 2 files changed, 15 insertions(+), 4 deletions(-)

diff --git a/okio/src/commonMain/kotlin/okio/Okio.kt b/okio/src/commonMain/kotlin/okio/Okio.kt
index 861d51121f..a0a420bbc3 100644
--- a/okio/src/commonMain/kotlin/okio/Okio.kt
+++ b/okio/src/commonMain/kotlin/okio/Okio.kt
@@ -49,13 +49,13 @@ private class BlackholeSink : Sink {
 
 /** Execute [block] then close this. This will be closed even if [block] throws. */
 inline fun <T : Closeable?, R> T.use(block: (T) -> R): R {
-  var result: R? = null
   var thrown: Throwable? = null
 
-  try {
-    result = block(this)
+  val result = try {
+    block(this)
   } catch (t: Throwable) {
     thrown = t
+    null
   } finally {
     try {
       this?.close()
@@ -69,5 +69,6 @@ inline fun <T : Closeable?, R> T.use(block: (T) -> R): R {
   }
 
   if (thrown != null) throw thrown
-  return result!!
+  @Suppress("UNCHECKED_CAST")
+  return result as R
 }
diff --git a/okio/src/nonWasmTest/kotlin/okio/UseTest.kt b/okio/src/nonWasmTest/kotlin/okio/UseTest.kt
index a36cf06867..3cf713b390 100644
--- a/okio/src/nonWasmTest/kotlin/okio/UseTest.kt
+++ b/okio/src/nonWasmTest/kotlin/okio/UseTest.kt
@@ -1,6 +1,7 @@
 package okio
 
 import kotlin.test.Test
+import kotlin.test.assertNull
 import okio.Path.Companion.toPath
 import okio.fakefilesystem.FakeFileSystem
 
@@ -25,4 +26,13 @@ class UseTest {
 
     fakeFileSystem.checkNoOpenFiles()
   }
+
+  @Test
+  fun acceptsNullReturn() {
+    val result = object : Closeable {
+      override fun close() {}
+    }.use { null }
+
+    assertNull(result)
+  }
 }